Fuel systems for gas turbine engines often include a fuel source and one or more pumps to deliver pressurized fuel to the combustor section of the engine. The fuel system typically includes a metering valve downstream of a pump to measure and regulate fuel flow to the combustor section and a bypass fuel line to recirculate fuel from a location between the pump and the metering valve to a location upstream of the pump. A typical fuel system also includes a pressure regulating valve to maintain a fixed differential pressure across the metering valve by controlling the fuel flowing through the bypass fuel line.
A common method of determining fuel flow through the fuel system includes using the position of the metering valve, also referred to as the metering valve stroke, to determine an associated fuel flow by referencing known fuel flow rates for the particular metering valve position values. However, this method assumes that the differential pressure across the metering valve is accurate with an ideal pressure regulating valve.
A need exists in the art for a reliable and accurate system and method for estimating fuel flow in a gas turbine engine with reduced reliance on pressure regulating valve accuracy.